U.S. patent application number 11/551410 was filed with the patent office on 2008-05-01 for low frequency electroacoustical transducing in a vehicle.
Invention is credited to Michael D. Rosen.
Application Number | 20080101645 11/551410 |
Document ID | / |
Family ID | 39314969 |
Filed Date | 2008-05-01 |
United States Patent
Application |
20080101645 |
Kind Code |
A1 |
Rosen; Michael D. |
May 1, 2008 |
LOW FREQUENCY ELECTROACOUSTICAL TRANSDUCING IN A VEHICLE
Abstract
An apparatus for generating low frequency acoustic signals in a
vehicle having an instrument panel is described. The apparatus
includes a baffle that is located at least partially within the
instrument panel. An electroacoustical transducer is mechanically
coupled to the baffle. The electroacoustical transducer generates
low frequency acoustic signals that radiate into a cavity within
the instrument panel and leak into the passenger compartment of the
vehicle.
Inventors: |
Rosen; Michael D.; (Weston,
MA) |
Correspondence
Address: |
FISH & RICHARDSON PC
P.O. BOX 1022
MINNEAPOLIS
MN
55440-1022
US
|
Family ID: |
39314969 |
Appl. No.: |
11/551410 |
Filed: |
October 20, 2006 |
Current U.S.
Class: |
381/389 ; 381/86;
381/89 |
Current CPC
Class: |
H04R 5/02 20130101; H04R
1/2834 20130101; H04R 2499/13 20130101; H04R 1/2819 20130101 |
Class at
Publication: |
381/389 ; 381/86;
381/89 |
International
Class: |
H04R 1/02 20060101
H04R001/02; H04B 1/00 20060101 H04B001/00 |
Claims
1. An apparatus for generating low frequency acoustic signals in a
vehicle having an instrument panel, the apparatus comprising: a
baffle that is located at least partially within the instrument
panel; and an electroacoustical transducer mechanically coupled to
the baffle, the electroacoustical transducer generating low
frequency acoustic signals that radiate into a cavity within the
instrument panel and leak into the passenger compartment of the
vehicle.
2. The apparatus of claim 1 further comprising a transducer
mechanically coupled to the electroacoustical transducer, the
transducer generating an acoustic signal in phase with the acoustic
signal generated by the electroacoustical transducer, the
transducer generating a mechanical vibration at least partially
canceling a mechanical vibration generated by the electroacoustical
transducer.
3. The apparatus of claim 1 wherein the one or more mechanical
openings do not include dedicated acoustic radiation paths for
guiding the acoustic signals to the passenger compartment from the
electroacoustical transducer.
4. The apparatus of claim 1 wherein the baffle is integrated with
the instrument panel.
5. The apparatus of claim 1 further comprising a structure that is
located within the instrument panel, the baffle being mechanically
coupled to the structure to create an enclosure for the
electroacoustical transducer.
6. The apparatus of claim 5 wherein the enclosure comprises a
ported enclosure.
7. The apparatus of claim 5 wherein the enclosure comprises a
sealed enclosure.
8. The apparatus of claim 5 wherein the enclosure comprises a bass
reflex enclosure.
9. The apparatus of claim 1 further comprising a user interface for
operating an electronics unit, the user interface being integrated
with the instrumental panel, and the electronics unit being
remotely located from the user interface.
10. The apparatus of claim 9 wherein the electroacoustical
transducer is located at least partially behind the user
interface.
11. The apparatus of claim 1 wherein the electroacoustical
transducer radiates energy in a frequency range of between about 60
Hz to 80 Hz.
12. The apparatus of claim 1 wherein the electroacoustical
transducer radiates energy in a frequency range of between about 20
Hz to 100 Hz.
13. The apparatus of claim 1 wherein the baffle is coupled to the
instrument panel through at least one mechanical isolator.
14. The apparatus of claim 1 further comprising a bass radiating
transducer that is remotely located from the instrument panel, the
bass radiating transducer radiating acoustic energy into the
passenger compartment of the vehicle.
15. The apparatus of claim 14 wherein the bass radiating transducer
is located in at least one of a rear package shelf, a vehicle door,
a rear corner post, and a rear hatch of the vehicle.
16. The apparatus of claim 1 wherein the electroacoustical
transducer comprises a radially magnetized cylindrical magnet
transducer.
17. The apparatus of claim 16 wherein the radially magnetized
cylindrical magnet transducer comprises one of a solid magnet and a
segmented magnet.
18. The apparatus of claim 1 wherein the electroacoustical
transducer comprises a moving magnet transducer.
19. The apparatus of claim 1 wherein the electroacoustical
transducer comprises a cup-type motor structure.
20. An audio system for a vehicle, comprising: a user interface
that is located in a passenger compartment of the vehicle; an
electronics unit that is remotely located from the user interface,
the electronics unit controlling an audio source; a baffle that is
located substantially behind an instrument panel of the vehicle;
and an electroacoustical transducer that is mechanically coupled to
the baffle, the electroacoustical transducer generating low
frequency acoustic signals.
21. The audio system of claim 20 wherein the electroacoustical
transducer radiates all the low frequency acoustic signals into a
cavity within the instrument panel that leak into the passenger
compartment of the vehicle through one or more mechanical openings
in the instrument panel.
22. The audio system of claim 21 wherein the one or more mechanical
openings do not include dedicated acoustic radiation paths for
guiding the acoustic signals to the passenger compartment from the
electroacoustical transducer.
23. The audio system of claim 20 wherein the user interface is
coupled to a steering wheel of the vehicle.
24. The audio system of claim 20 wherein the user interface is
coupled to the instrument panel of the vehicle.
25. The audio system of claim 20 wherein the baffle is located
behind the user interface.
26. The audio system of claim 20 wherein the baffle is coupled to
the instrument panel through at least one mechanical isolator.
27. The audio system of claim 20 further comprising a structure
that is located within the instrument panel, the baffle being
mechanically coupled to the structure to create an enclosure for
the electroacoustical transducer.
28. The audio system of claim 27 wherein enclosure comprises a
ported enclosure.
29. The audio system of claim 27 wherein enclosure comprises a
sealed enclosure.
30. The audio system of claim 27 wherein the enclosure comprises a
bass reflex enclosure.
31. The audio system of claim 27 wherein the enclosure comprises an
acoustic waveguide.
32. The audio system of claim 27 wherein a volume of the enclosure
is less than two liters.
33. The audio system of claim 27 wherein the enclosure radiates
acoustic waves in a frequency range of between about 60 Hz to 80
Hz.
34. The audio system of claim 27 wherein the enclosure is mounted
to the instrument panel through at least one mechanical
isolator.
35. The audio system of claim 20 further comprising a bass
radiating transducer that is remotely located from the instrument
panel, the bass radiating transducer radiating acoustic energy into
the passenger compartment of the vehicle.
36. The audio system of claim 35 wherein the bass radiating
transducer is located in at least one of a rear package shelf, a
vehicle door, a rear corner post, and a rear hatch of the
vehicle.
37. A method for generating low frequency acoustic signals in a
vehicle having an instrument panel, the method comprising: locating
a baffle at least partially within the instrument panel;
mechanically coupling an electroacoustical transducer to the
baffle; radiating low frequency acoustic signals from the
electroacoustical transducer into a cavity within the instrument
panel; and leaking the low frequency acoustic signals into the
passenger compartment of the vehicle.
38. The method of claim 37 further comprising reducing a vibration
in the baffle caused by the electroacoustical transducer with a
transducer mechanically coupled to the electroacoustical
transducer, the transducer driven mechanically out of phase with
the electroacoustical transducer and acoustically in phase with the
electroacoustical transducer.
39. The method of claim 37 wherein the low frequency acoustic
signals are radiated through non-dedicated acoustic radiation paths
that guide the low frequency acoustic signals to the one or more
mechanical openings in the instrument panel.
40. The method of claim 37 wherein the baffle is integrated with
the instrument panel.
41. The method of claim 37 further comprising coupling the baffle
to a structure to create an enclosure for the electroacoustical
transducer.
42. The method of claim 41 further comprising substantially
isolating the enclosure from the instrument panel.
43. The method of claim 37 further comprising substantially
isolating the baffle from the instrument panel.
44. The method of claim 37 further comprising locating a bass
radiating transducer remotely from the instrument panel, the bass
radiating transducer radiating acoustic energy into the passenger
compartment of the vehicle.
45. The method of claim 44 wherein the bass radiating transducer is
located in at least one of a rear package shelf, a vehicle door, a
rear corner post, and a rear hatch of the vehicle.
46. An apparatus for generating low frequency acoustic signals in a
vehicle having an instrument panel, the apparatus comprising: an
electroacoustical transducer that is located behind the instrument
panel, the electroacoustical transducer generating low frequency
acoustic signals that radiate into a cavity within the instrument
panel and leak into the passenger compartment of the vehicle; and a
low frequency transducer that is located in a rear section of the
passenger compartment, the low frequency transducer radiating low
frequency acoustic signals to the passenger compartment of the
vehicle.
47. The apparatus of claim 46 wherein the one or more mechanical
openings do not include dedicated acoustic radiation paths for
guiding the acoustic signals to the passenger compartment from the
electroacoustical transducer.
48. The apparatus of claim 46 wherein the electroacoustical
transducer radiates energy in a frequency range of between about 60
Hz to 80 Hz.
49. The apparatus of claim 46 wherein the electroacoustical
transducer radiates energy in a frequency range of between about 20
Hz to 100 Hz.
50. The apparatus of claim 46 wherein the low frequency transducer
is located in at least one of a rear package shelf, a vehicle door,
a rear corner post, and a rear hatch of the vehicle.
51. An apparatus for generating low frequency acoustic signals in a
vehicle having an instrument panel, the apparatus comprising: means
for locating a baffle at least partially within the instrument
panel; means for mechanically coupling an electroacoustical
transducer to the baffle; and means for radiating low frequency
acoustic signals from the electroacoustical transducer into a
cavity within the instrument panel, the low frequency acoustic
signals leaking into the passenger compartment of the vehicle.
Description
BACKGROUND OF THE INVENTION
[0001] Automotive sound systems typically include multiple
loudspeakers positioned in various locations around the passenger
compartment of the vehicle. Typical loudspeaker locations include
the vehicle door panels and the interior trim panels. Low-frequency
reproducing speakers, also known as woofers, are typically located
in the rear package shelf of a vehicle. The rear package shelf acts
as a baffle between the passenger compartment and the trunk of the
vehicle.
SUMMARY OF THE INVENTION
[0002] In one aspect, the invention is embodied in an apparatus for
generating low frequency acoustic signals in a vehicle having an
instrument panel. The apparatus includes a baffle that is located
at least partially within the instrument panel. An
electroacoustical transducer is mechanically coupled to the baffle.
The electroacoustical transducer generates low frequency acoustic
signals that radiate into a cavity within the instrument panel and
leak into the passenger compartment of the vehicle through one or
more mechanical openings in the instrument panel.
[0003] In one embodiment, the mechanical openings do not include
dedicated acoustic radiation paths for guiding the acoustic signals
to the passenger compartment from the electroacoustical transducer.
In one embodiment, the baffle is integrated with the instrument
panel. In one embodiment, a structure is located within the
instrument panel and the baffle is mechanically coupled to the
structure to create an enclosure for the electroacoustical
transducer. The enclosure can be a ported enclosure, a sealed
enclosure, or a bass reflex enclosure, for example.
[0004] The apparatus can further include a transducer that is
mechanically coupled to the electroacoustical transducer. The
transducer generates acoustic signals in phase with the acoustic
signals generated by the electroacoustical transducer. The
transducer generates a mechanical vibration that at least partially
cancels a mechanical vibration generated by the electroacoustical
transducer.
[0005] The apparatus can also include an audio source having a user
interface and an electronics unit that is remotely located from the
user interface. The electroacoustical transducer can be located at
least partially behind the user interface.
[0006] In one embodiment, the electroacoustical transducer radiates
energy in a frequency range of between about 60 Hz to 80 Hz. In
another embodiment, the electroacoustical transducer radiates
energy in a frequency range of between about 20 Hz to 100 Hz. The
baffle can be coupled to the instrument panel through at least one
mechanical isolator.
[0007] The apparatus can also include a bass radiating transducer
that is remotely located from the instrument panel. The bass
radiating transducer radiates acoustic energy into the passenger
compartment of the vehicle. The bass radiating transducer can be
located in a rear package shelf, a vehicle door, a rear corner
post, or a rear hatch of the vehicle, for example.
[0008] The electroacoustical transducer can include a radially
magnetized cylindrical magnet transducer. The radially magnetized
cylindrical magnet transducer can include a solid magnet or a
segmented magnet. The electroacoustical transducer can include a
moving magnet transducer. The electroacoustical transducer can
include a cup-type motor structure.
[0009] In another aspect, the invention is embodied in an audio
system for a vehicle. The audio system includes a user interface
that is located in a passenger compartment of the vehicle. An
electronics unit is remotely located from the user interface. The
electronics unit controls the audio source. The audio system also
includes a baffle that is located substantially behind an
instrument panel of the vehicle. An electroacoustical transducer is
mechanically coupled to the baffle. The electroacoustical
transducer generates low frequency acoustic signals that radiate
into a cavity within the instrument panel and leak into the
passenger compartment of the vehicle through one or more mechanical
openings in the instrument panel.
[0010] In one embodiment, the electroacoustical transducer radiates
all the low frequency acoustic signals into a cavity within the
instrument panel that leak into the passenger compartment of the
vehicle only through one or more mechanical openings in the
instrument panel. In one embodiment, the one or more mechanical
openings do not include dedicated acoustic radiation paths for
guiding the acoustic signals to the passenger compartment from the
electroacoustical transducer.
[0011] The audio system can also include non-dedicated acoustic
radiation paths that guide the acoustic signals to the mechanical
openings in the instrument panel. The user interface can be coupled
to a steering wheel of the vehicle. The user interface can
alternatively be coupled to the instrument panel of the vehicle.
The baffle can be located behind the user interface. The baffle can
be coupled to the instrument panel through one or more mechanical
isolators. The audio system can radiate bass signals from both
front and rear of the vehicle. The audio system can radiate all
bass signals from a single unit front low-frequency
loudspeaker.
[0012] In one embodiment, the audio system can include an enclosure
that is located within the instrument panel. The baffle is
mechanically coupled to a structure to create the enclosure for the
electroacoustical transducer. The enclosure can be a ported
enclosure, a sealed enclosure, or a bass reflex enclosure, for
example. In one embodiment, the enclosure includes an acoustic
waveguide. A volume of the enclosure can be less than two liters.
The enclosure can radiate acoustic waves in a frequency range of
between about 60 Hz to 80 Hz. The enclosure can be mounted to the
instrument panel through at least one mechanical isolator.
[0013] In one embodiment, the audio system also includes a bass
radiating transducer that is remotely located from the instrument
panel. The bass radiating transducer radiates acoustic energy into
the passenger compartment of the vehicle. The bass radiating
transducer can be located in a rear package shelf, a vehicle door,
a rear corner post, or a rear hatch of the vehicle, for
example.
[0014] In yet another aspect, the invention is embodied in a method
for generating low frequency acoustic signals in a vehicle having
an instrument panel. The method includes locating a baffle at least
partially within the instrument panel. An electroacoustical
transducer is mechanically coupled to the baffle. Low frequency
acoustic signals are radiated from the electroacoustical transducer
into a cavity within the instrument panel. The low frequency
acoustic signals leak into the passenger compartment of the vehicle
through one or more mechanical openings in the instrument
panel.
[0015] The method can also include reducing a vibration in the
baffle caused by the electroacoustical transducer with a transducer
mechanically coupled to the electroacoustical transducer. The
transducer is driven mechanically out of phase with the
electroacoustical transducer and acoustically in phase with the
electroacoustical transducer.
[0016] In one embodiment, non-dedicated acoustic radiation paths
guide the acoustic signals to the mechanical openings in the
instrument panel. The baffle can be integrated with the instrument
panel. The baffle can be coupled to a structure to create an
enclosure for the electroacoustical transducer. The enclosure can
be substantially isolated from the instrument panel. The baffle can
be substantially isolated from the instrument panel. A bass
radiating transducer can be remotely located from the instrument
panel. The bass radiating transducer radiates acoustic energy into
the passenger compartment of the vehicle. The bass radiating
transducer can be located in a rear package shelf, a vehicle door,
a rear corner post, or a rear hatch of the vehicle, for
example.
[0017] One aspect of the invention is embodied in an apparatus for
generating low frequency acoustic signals in a vehicle having an
instrument panel. The apparatus includes an electroacoustical
transducer that is located behind the instrument panel. The
electroacoustical transducer generates low frequency acoustic
signals that radiate into a cavity within the instrument panel and
leak into the passenger compartment of the vehicle through one or
more mechanical openings in the instrument panel. The apparatus
also includes a low frequency transducer that is located in a rear
section of the passenger compartment. The low frequency transducer
radiates low frequency acoustic signals to the passenger
compartment of the vehicle.
[0018] In one embodiment, the one or more mechanical openings do
not include dedicated acoustic radiation paths for guiding the
acoustic signals to the passenger compartment from the
electroacoustical transducer. In one embodiment, the
electroacoustical transducer and the low frequency transducer are
driven with identical audio signals. In another embodiment, the
electroacoustical transducer and the low frequency transducer are
driven with different audio signals. In one embodiment, at least
one of the electroacoustical transducer and the low frequency
transducer radiates energy in a frequency range of between about 60
Hz to 80 Hz. In another embodiment, at least one of the
electroacoustical transducer and the low frequency transducer
radiates energy in a frequency range of between about 20 Hz to 100
Hz. The low frequency transducer can be located in a rear package
shelf, a vehicle door, a rear corner post, or a rear hatch of the
vehicle, for example.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] This invention is described with particularity in the
detailed description. The above and further advantages of this
invention may be better understood by referring to the following
description in conjunction with the accompanying drawings, in which
like numerals indicate like structural elements and features in
various figures. The drawings are not necessarily to scale,
emphasis instead being placed upon illustrating the principles of
the invention.
[0020] FIG. 1 is a perspective view of the interior of a vehicle
having a vehicle instrument panel;
[0021] FIG. 2 is a perspective view of the interior of the vehicle
with the control interface removed from the instrument panel;
[0022] FIG. 3A through FIG. 3F illustrate various configurations of
low-frequency transducers according to the invention;
[0023] FIG. 4 is a perspective view of the interior of the vehicle
according to another embodiment of the invention;
[0024] FIG. 5 illustrates a vehicle audio system according to one
embodiment of the invention; and
[0025] FIG. 6 is a diagram of a multiple channel surround sound
system for a vehicle according to the invention.
DETAILED DESCRIPTION
[0026] It is advantageous in a vehicle audio system to generate low
frequency acoustic signals from the front area of the passenger
compartment. This improves the overall quality of low frequency
acoustic signals compared to those that are generated purely only
in the rear area of the passenger component. For example, a bass
transducer located in the front of the passenger compartment can
generate low frequency acoustic signals that enhance the various
low frequency modes in the passenger compartment.
[0027] Unfortunately, the volume required to produce adequate low
frequency acoustic signals from the front of the vehicle is
generally not available. For example, the instrument panel in most
vehicles contains instruments, stereo equipment, computer
electronics and climate control electronics, mechanics, and air
conditioning duct work.
[0028] FIG. 1 is a perspective view of the interior of a vehicle
100 having a vehicle instrument panel 102. The instrument panel 102
contains displays 104 that show the speed of the vehicle, fuel
level, coolant temperature, speed of the engine, as well as other
vehicle parameters. The instrument panel 102 also includes the
climate control system 106 and the audio system 108. Most
factory-installed audio systems include a control interface 110
that is accessible to the driver and front passenger and an
electronics unit (not shown) that is controlled by the control
interface 110. For convenience, the control interface 110 is
usually located near the center of the instrument panel 102 but is
not limited to this location. For example, audio controls may be
located on the steering wheel or on a console between the driver
and passenger seats.
[0029] The electronics unit can include amplifier circuits, tuners,
equalization circuits, memory as well as other circuitry. The
electronics unit is typically located behind the control interface
110 within a volume space of the instrument panel 102.
[0030] In one embodiment, the electronics unit is positioned in a
location other than behind the control interface 110. For example,
the electronics unit can be remotely located from the instrument
panel 102. Alternatively, the electronics unit can be located in
the instrument panel 102, but in a location that is not directly
behind the control interface 110.
[0031] In one embodiment, the volume of space behind the control
interface 110 that is normally occupied by the electronics unit can
be used by a low frequency transducer. The low frequency transducer
can be coupled to a baffle. The low frequency transducer can
alternatively be coupled to an enclosure. In one embodiment, a
baffle having a transducer can be coupled to a separate structure
which creates an enclosure to contain or alter the back wave
radiation from the transducer. The baffle can be located at least
partially within the instrument panel 102. A low frequency
electroacoustical transducer is mechanically coupled to the baffle.
The low frequency electroacoustical transducer generates low
frequency acoustic signals that radiate into a cavity within the
instrument panel 102 and leak into the passenger compartment of the
vehicle through mechanical openings (see below for more details) in
the instrument panel. The path length between the acoustic waves
propagating from the back of the transducer and the acoustic waves
propagating from the front of the transducer is chosen to reduce
acoustic wave cancellation.
[0032] Low frequency acoustic signals are generally non-directional
due to the wavelength at which they propagate. These low-frequency
acoustic signals do not require dedicated transmission paths to
effectively transmit acoustic energy into the passenger compartment
of the vehicle. Instead, the low frequency acoustic energy is
allowed to leak through the instrument panel into the passenger
compartment. A typical instrument panel is not air-tight due to the
many gaps in the instrument panel. For example, the instrument
panel may be comprised of several sections joined together into a
single panel. The seams between the sections are usually not
air-tight and air can move through the instrument panel through
these gaps. A gap may be created when a display or control does not
tightly fit its cutout in the instrument panel. Other gaps in the
instrument panel may be designed into the panel as vents or access
holes to provide easy access during installation. These gaps are
not intentionally designed to provide an acoustic path through the
instrument panel and are hereinafter referred as non-acoustic
paths. The inventors have discovered that these non-acoustic paths
are sufficient for transmitting the low-frequency acoustic signals
through the instrument panel into the passenger compartment.
Furthermore, using the non-acoustic paths through the instrument
panel eliminates the need for specifically-designed acoustic
elements such as ducts, tubes, and waveguides. Elimination of these
acoustic-specific elements frees up the space behind the instrument
panel and also allows greater freedom in aesthetic design of the
instrument panel. As used herein, "leak" refers to a non-acoustic
path through the instrument panel. As used herein, "leaking" refers
to the transmission of acoustic signals from an electroacoustical
transducer to a listening area by the exclusive use of a
non-acoustic path.
[0033] In some embodiments, various electronic devices can be
coupled to the audio system. For example, the electronic devices
can include CD changers, GPS receivers, navigation systems, MP3
players, DVD players, and/or satellite radio receivers. One or more
of these electronic devices can be located behind the control
interface 110. Some vehicle instrument panels can include one or
more mounting slots 112, 114. The mounting slots 112, 114 can
accommodate electronic devices.
[0034] FIG. 2 is a perspective view of the interior of the vehicle
100 with the control interface 110 removed from the instrument
panel 102. The electronics unit (not shown) is remotely located
from behind the control interface 110. In one embodiment, the
volume of space 116 behind the control interface 110 houses a
low-frequency transducer 118 that can generate low-frequency
acoustic signals. In one embodiment, the transducer 118 can be
coupled to a baffle. The baffle can be coupled to a separate
structure to create an enclosure 120 which can be further
mechanically coupled to the instrument panel. The enclosure 120 can
be less than two liters. The low-frequency transducer 118 can have
a relatively small diameter, such as less than six inches. In other
embodiments, multiple transducers can also be coupled to the baffle
or enclosure 120. The enclosure 120 can embody a sealed enclosure,
a ported enclosure, an enclosure including a waveguide structure,
an enclosure including a passive radiator, or any other type of
suitable enclosure.
[0035] The control interface 110 can include various controls, such
as pushbuttons, rotary controls, scroll wheels, a touch screen
including softkeys, and/or joysticks. An example of such a control
interface 110 is described in pending U.S. patent application Ser.
No. 10/626,349 filed on Jul. 23, 2003, entitled "System and Method
for Accepting a User Control Input."
[0036] The low-frequency transducer 118 generates low-frequency
acoustic signals from the front of the passenger compartment of the
vehicle 100. The low frequency transducer 118 preferably has a
small diameter and operates in a frequency range of between about
20 Hz to 300 Hz. The enclosure 120 can have a volume of less than
two liters. In one embodiment, the enclosure 120 can be located in
the volume of space 116.
[0037] FIG. 3A through FIG. 3F illustrate various configurations of
low-frequency transducers according to the invention. Specifically,
FIG. 3A illustrates a low-frequency transducer 300 that is mounted
in a baffle 302. The baffle 302 is positioned within an instrument
panel of a vehicle such that one side 304 of the baffle 302 is
acoustically isolated from the other side 306 of the baffle 302. In
some embodiments, the baffle 302 does not fully isolate one side
304 from the other side 306. For example, the edges of the baffle
302 can include leakage paths. The baffle 302 increases the
effective path length between the front and back sides of the
transducer 300, which may increase radiation efficiency. The baffle
302 can be mounted in any suitable orientation. In one embodiment,
the baffle 302 is coupled to an interior structure of the
instrument panel thereby enclosing a portion of the interior volume
of the instrument panel. In this embodiment, the baffle 302 and the
interior structure of the instrument panel together act as an
enclosure for the transducer 300.
[0038] FIG. 3B illustrates an embodiment of an enclosure 310
including a low-frequency transducer 312 according to one
embodiment of the invention. The enclosure 310 is a sealed
enclosure that is adapted to receive the low-frequency transducer
312. In one embodiment, the volume of the enclosure 310 is less
than about two liters. In one embodiment, the diameter of the
low-frequency transducer 312 is less than six inches. The enclosure
310 is shaped to maximize the interior volume of air, while
corresponding to the mounting dimensions of the space provided
within the instrument panel.
[0039] The enclosure 310 can be a sealed enclosure, a ported
enclosure, or any other suitable type of enclosure. The enclosure
310 can also include one or more passive radiators and/or a
waveguide structure. In one embodiment, acoustic energy from the
transducer 312 as well as the port, passive radiator, or waveguide
opening, if present, escapes into the passenger compartment of the
vehicle through one or more mechanical openings such as seams,
cracks, vents, and/or other voids in the instrument panel.
Specifically, in some embodiments, sound from the transducer leaks
into the passenger compartment solely through non-dedicated sound
transmission paths that guide sound radiation from the transducer
to the one or more mechanical openings in the instrument panel.
[0040] Input terminals of the low-frequency transducer 312 are
coupled to output terminals of an electronics unit (not shown). The
electronics unit can include a band pass filter or a low pass
filter that transmits only low frequency audio signals to the
transducer 312. Alternatively, the transducer 312 can include a
cross-over network that prevents unwanted frequency signals from
being reproduced by the low-frequency transducer 312.
[0041] FIG. 3C illustrates a low-frequency transducer 320 coupled
to an irregular-shaped enclosure 322. The irregular-shaped
enclosure 322 is designed to fit into a specific space within the
instrument panel. For example, the irregular-shaped enclosure 322
can be designed such that its internal volume is maximized. The
irregular-shaped enclosure 322 can be a sealed enclosure, a ported
enclosure, an enclosure including a waveguide structure, an
enclosure including a passive radiator, or any other type of
suitable enclosure. In one embodiment, the volume of the
irregular-shaped enclosure 322 is less than two liters.
[0042] As previously described, the instrument panel within which
the enclosure 322 is mounted can be buzz/vibration-prone. This is
due at least in part to the design and materials used to fabricate
the instrument panel. For example, an energized transducer driver
develops forces which cause the diaphragm of the transducer to move
relative to the transducer frame. Some of these forces are
transmitted through the frame to the enclosure 322 and through the
enclosure 322 to the instrument panel. The energized transducer can
cause the instrument panel to vibrate excessively, especially when
the forces applied to the instrument panel are around its modal
frequencies. This excessive vibration in the instrument panel can
be acoustically perceived as unwanted buzzes and rattles causing
degraded frequency response of radiated sound. Vibration canceling
techniques can be used to mitigate the vibration. One such
technique is described with reference to FIG. 3D.
[0043] FIG. 3D illustrates an enclosure 330 including two
low-frequency transducers 332, 334. The low-frequency transducers
332, 334 are positioned on opposing surfaces of the enclosure 330.
In one embodiment, the low-frequency transducers 332, 334 are
substantially identical. The low-frequency transducers 332, 334 can
be driven with identical audio signals. In one configuration, the
transducers 332, 334 can be driven with audio signals having the
same polarity. Alternatively, the transducers 332, 334 can be
driven with audio signals having opposite polarity. The transducers
332, 334 are mounted such that they move mechanically out of phase
when driven with the audio signals, and also radiate acoustically
in phase. For example, the transducers 332, 334 can be driven
mechanically out-of-phase such that forces generated by the first
transducer 332 are at least partially cancelled by forces from the
second transducer 334. This configuration is sometimes referred to
as a dual opposed transducer configuration. Examples of dual
opposed transducer configurations are described in U.S. Pat. No.
6,985,593 issued on Jan. 10, 2006 entitled "Baffle Vibration
Reducing" and pending U.S. patent application Ser. No. 10/623,996
filed on Jul. 21, 2003 entitled "Passive Acoustical Radiating",
incorporated herein by reference.
[0044] The transducers 332, 334 do not have to be mounted in a
parallel configuration to effectively reduce a resultant force on
the enclosure. Transducers 332, 334 are not required to be
identical to each other. For example, one of the transducers may be
a moving mass that reduces the vibration generated by the other
transducer but does not radiate a significant acoustic signal
relative to the acoustic signal generated by the other
transducer.
[0045] Other techniques for reducing vibration in the instrument
panel according to the invention include mechanically isolating the
enclosure 330 from the instrument panel or mechanically isolating a
transducer from the baffle of the enclosure 330. For example, the
enclosure 330 can be coupled to the instrument panel through one or
more mechanical isolators. A suitable mechanical isolator can
include, but is not limited to, an elastomer member, a spring, a
dashpot, and a shock absorber. The mechanical isolator reduces the
amplitude of the mechanical vibration that is coupled into the
instrument panel. Examples of mechanical vibration isolation
techniques are described in pending U.S. patent application Ser.
No. 10/932,137 filed on Sep. 1, 2004 entitled "Audio System for
Portable Device", incorporated herein by reference. It should be
noted that the vibration cancelling techniques described herein can
be used with various enclosure configurations and transducers. In
addition, a combination of the vibration cancellation techniques
described above and mechanical isolation can also be used.
[0046] FIG. 3E illustrates an enclosure 340 including two
low-frequency transducers 342, 344 according to another embodiment
of the invention. The two low-frequency transducers 342, 344 are
coupled together through motor structures 346, 348. This
configuration is generally more compact than the configuration of
FIG. 3D. In one configuration, the motor structures 346, 348 are
separated. In this configuration, the baskets of the transducers
342, 344 are coupled to opposite sides of the enclosure 340.
[0047] In one embodiment, the low-frequency transducers 342, 344
are substantially identical. The low-frequency transducers 342, 344
can be driven with identical audio signals having the same phase.
In this embodiment, acoustic energy from the front surface of the
transducers 342, 344 and acoustic energy from the rear surface of
the transducers 342, 344 combines to increase acoustic output
energy. For example, in one configuration, the front surface of
each transducer 342, 344 can radiate acoustic energy into the
interior of the instrument panel while the rear surface of each of
the transducers 342, 344 can radiate acoustic energy through the
opening 345 indirectly into the passenger compartment of the
vehicle through one or more non-dedicated mechanical openings in
the instrument panel such as seams, cracks, vents, and/or other
voids. The path length between the front and rear surfaces of the
transducers 342, 344 to the passenger compartment is configured to
maximize acoustic efficiency. As previously described, the
transducers 342, 344 can be driven mechanically out-of-phase such
that forces generated by the first transducer 342 are generally
cancelled by forces from the second transducer 344.
[0048] FIG. 3F illustrates an enclosure 350 including two
low-frequency transducers 352, 354 according to another embodiment
of the invention. The two low-frequency transducers 352, 354 are
coupled to opposite sides of the enclosure 350. Acoustic energy
from the rear surfaces of the transducers 352, 354 radiate into the
instrument panel while acoustic energy from the front surfaces of
the transducers 352, 354 radiates into the enclosure 350. As
previously described, the enclosure 350 can be any suitable
enclosure type.
[0049] In one embodiment, the low-frequency transducers 352, 354
are substantially identical. The low-frequency transducers 352, 354
can be driven with identical audio signals that are substantially
in phase. The transducers 352, 354 are mounted such that they move
mechanically out of phase when driven with in phase electrical
signals, and also radiate acoustically in phase. For example, the
transducers 352, 354 can be driven mechanically out-of-phase such
that forces generated by the first transducer 352 are generally
cancelled by forces from the second transducer 354.
[0050] In one embodiment, in the various configurations of
low-frequency transducers according to FIG. 3A through FIG. 3F,
acoustic energy from the transducer(s) radiate into a cavity of the
instrument panel and escapes into the passenger compartment of the
vehicle through one or more mechanical openings such as seams,
cracks, vents, and/or other voids in the instrument panel without
any dedicated sound transmission path for guiding sound radiation
from the transducer to the one or more mechanical openings.
[0051] It should be noted that all of the configurations described
herein can include transducers having various motor structures. For
example, radially magnetized cylindrical motor structures can
provide increased motor force for a given size motor structure as
compared to standard motor structures. The radially magnetized
motor structure can include solid or segmented magnets.
Additionally, the motor can include a moving coil or moving magnet
structure. Other motor structures can also be used such as a pot
type motor structure, a ceramic type structure having a donut
shaped magnet, or any other suitable motor structure.
[0052] FIG. 4 is a perspective view of the interior of the vehicle
400 according to another embodiment of the invention. An instrument
panel 402 includes a control interface 404. In this embodiment, an
enclosure 406 including a low-frequency transducer 408 is located
in a 1-DIN, 2-DIN or any suitably sized slot in the instrument
panel 402. FIG. 4 illustrates that the enclosure 406 is not
required to be located directly behind the control interface 404.
The enclosure 406 can be positioned in any suitable unoccupied
internal space within the instrument panel 402. The enclosure 406
can be a sealed enclosure, a ported enclosure, or any other
suitable low-frequency enclosure type.
[0053] The control interface 404 includes at least one rotary
control 410. A display 412 is located above the rotary control 410.
A slot 414 is located below the rotary control 410. The slot 414 is
designed to accept a compact disk (CD) or a digital video disk
(DVD), for example.
[0054] The low-frequency electroacoustical transducer 408 located
within the instrument panel 402 generates low frequency acoustic
signals that radiate into a cavity within the instrument panel 402
and leak into the passenger compartment of the vehicle through
mechanical openings in the instrument panel 402. In one embodiment,
there are no dedicated acoustic radiation paths such as ducks,
tubes, waveguides which guide the acoustic signals to the
mechanical openings in the instrument panel 402. For example,
acoustic signals generated by the transducer 408 only propagate
through cracks, seams, and voids in the instrument panel 402.
[0055] In one embodiment, the acoustic signals can propagate
through one or more climate control vents 416 in the instrument
panel 402. This can present design challenges since the air
handling ducts are generally well isolated from other components
within the instrument panel and will not allow substantial acoustic
energy to leak into them. It should be understood, however, that an
air handling duct generally would not behave as a tuned acoustic
waveguide for any low-frequency acoustic energy that leaks into it.
Embodiments of the present invention take advantage of sound
leaking through openings not designed for the purpose of conducting
sound from inside the instrument panel to the passenger
compartment. For example, these techniques do not rely on dedicated
acoustic paths from the acoustic source within the instrument panel
to the passenger compartment.
[0056] FIG. 5 illustrates a vehicle audio system 500 according to
one embodiment of the invention. The vehicle audio system 500
includes a control interface 502 and an electronics unit 504. The
electronics unit 504 can be remotely located from the control
interface 502. The control interface 502 can include one or more
rotary 506 and/or push button controls 508. The control interface
502 may include a slot 510 that is configured to accept a compact
disk (CD) or a digital video disk (DVD), for example. In one
embodiment, the control interface 502 can also include a display
512. The display 512 can be a liquid crystal display (LCD), cathode
ray tube (CRT), or a plasma display, for example. The display 512
can be a touch screen display.
[0057] The control interface 502 is electrically coupled to the
electronics unit 504 through a signal transmission line 514. In one
embodiment, the signal transmission line 514 is a bus that couples
various systems in the vehicle together. For example, the signal
transmission line 514 can couple the central processing unit (CPU)
516 of the vehicle to the control interface 502 and the electronics
unit 504. Although the connections between components are shown as
hard-wired, wireless connections can also be used.
[0058] The control interface 502 and the electronics unit 504 can
also be coupled to a power source 518 through one or more power
lines 519. The power source 518 can include the battery and/or
alternator of the vehicle. In one embodiment (not shown), the
signal transmission line 514 can include a power line that can be
coupled to the power source 518. The power source 518 can also be
coupled to the CPU 516.
[0059] An antenna 520 is coupled to the electronics unit 504. For
example, the antenna 520 can be an AM/FM antenna, a satellite
antenna, a Bluetooth antenna, or a combination thereof.
[0060] The electronics unit 504 can also include an optical digital
output terminal 522 that outputs an optical signal. The optical
digital output terminal 522 is coupled to a signal processor 524
such as a 5.1 channel processor through an optical signal
transmission line 525. The signal processor 524 receives the
optical signal. The signal processor 524 can embody a digital
signal processor (DSP) or can be fabricated from analog circuitry.
The signal processor 524 can operate on the optical signal in
various ways. For example, the signal processor 524 can provide
decoding, alter the signal gain, and/or mix signals in order to
create analog output signals. Analog output terminals 526 on the
signal processor 524 output the analog output signals. In another
embodiment, a non-optical output terminal can be coupled to a DSP
through a wired electrical connection.
[0061] One or more amplifiers can be coupled to the analog output
terminals 526. The amplifiers are connected to loudspeakers located
throughout the passenger compartment of the vehicle. One such
amplifier 528 is coupled to a low frequency transducer 530 that is
located within the instrument panel of the vehicle.
[0062] FIG. 6 is a diagram of a multiple channel surround sound
system 600 for a vehicle 602 according to the invention. The
multiple channel surround sound system 600 includes a low-frequency
transducer 604 located in the instrument panel of the vehicle 602.
In one embodiment, the low-frequency transducer 604 can reproduce
frequencies in the range of about 20 Hz to 200 Hz. In one
embodiment, the low-frequency transducer 604 can reproduce
frequencies in the range of about 60 Hz to 80 Hz. Although FIG. 6
illustrates a multi-channel surround sound system, it should be
understood that the principles and techniques described herein can
also be used in a traditional stereo system.
[0063] The multiple channel surround system 600 includes a control
interface 606 and an electronics unit 608. As previously discussed,
the electronics unit 608 can be remotely located from the control
interface 606. The electronics unit 608 is coupled to a signal
processor 610. The signal processor 610 can perform various
functions on audio signals that are received from the electronics
unit 608. For example, the signal processor 610 can provide
equalization and/or downmixing to the audio signals.
[0064] In one embodiment, the system 600 includes a plurality of
discrete surround sound signals. For example, the plurality of
signals can correspond to a front left (FL) channel 612, a front
right (FR) channel 614, a center (C) channel 616, a surround left
(SL) channel 618, a surround right (SR) channel 620, a bass or low
frequency effects (LFE) channel 622, and a specific low-frequency
channel 624 to drive the low-frequency transducer 604 located
within the instrument panel. Although seven channels are shown and
described, any number of channels can be utilized. For example, in
one embodiment, the center channel 616 is removed. Alternatively,
the system 600 can include a surround center channel (not
shown).
[0065] Output signals from the signal processor 608 can be sent to
spatially diverse transducers positioned in various locations
within the vehicle 602. The transducers can include a front left
speaker (FL-S) 632, a center speaker (C-S) 634, a front right
speaker (FR-S) 636, a surround left speaker (SL-S) 638, a
low-frequency rear speaker (LFR-S) 640 also referred to as a bass
radiating transducer, a surround right speaker (SR-S) 642, and the
low-frequency loudspeaker 604. The speakers can be installed in
various locations throughout the vehicle 602. For example, the
low-frequency loudspeaker 604 can be installed in the instrument
panel and the bass radiating transducer 640 can be located in the
rear package shelf of the vehicle 602. In other embodiments, the
bass radiating transducer 640 can also located in a vehicle door,
such as a rear vehicle door, a rear corner post, or a rear hatch of
the vehicle. The bass radiating transducer 640 and the
low-frequency loudspeaker 604 can be driven with the same low
frequency signal or can be driven with different low frequency
signals. In this implementation, low frequency sound can be
generated from both front and rear locations in the vehicle 602.
The front left speaker 632 and the front right speaker 636 can be
mounted in the front left and front right door panels,
respectively, of the vehicle 602. Any number of transducers can be
installed in the vehicle 602 in various locations regardless of the
number of signal channels in the system 600.
[0066] In one embodiment, low frequency performance is enhanced by
radiating low frequency sound from both the front and the rear of
the vehicle. This configuration provides greater flexibility for
bass imaging management, such as providing enhanced perceived bass
imaging or increased maximum low frequency output level, or both to
passengers in both the front and rear seats of the vehicle.
[0067] In another embodiment, the bass radiating transducer 640 is
omitted and all bass signals are radiated from the single unit
front low-frequency loudspeaker 604.
[0068] Skilled artisans will appreciate that although various
openings in the instrument panel are shown and described for
radiating low frequency sound from the front of the passenger
compartment of the vehicle, the low frequency transducer does not
require existing or specifically designed dedicated vent openings
for radiating low frequency sound. The low frequency sound can be
leaked into the passenger compartment through any voids in the
instrument panel.
[0069] While the invention has been particularly shown and
described with reference to specific exemplary embodiments, it is
evident that those skilled in the art may now make numerous
modifications of, departures from and uses of the specific
apparatus and techniques herein disclosed. Consequently, the
invention is to be construed as embracing each and every novel
feature and novel combination of features presented in or possessed
by the apparatus and techniques herein disclosed and limited only
by the spirit and scope of the appended claims.
* * * * *